1. Field of the Invention
The present invention generally relates to a method and system for highlighting a topic element. In particular, a method and system for selecting highlighting color for a topic element in a chart having a plurality of contrast elements of a plurality of colors is presented.
2. Description of the Related Art
In a chart display, color is a very basic and important means of expression used for differentiating different types of elements in a chart. In many chart applications, there is an increasing number of elements in a chart, and the types of elements are becoming increasingly complicated. Consequently, it becomes necessary to use reasonable colors to represent respective types of elements so as to enable a user to obtain information of interest from the chart. FIG. 1 shows a flowchart of the Websphere business model that is relatively simple; however, it still has a lot of control nodes and general flow nodes. How to differentiate these nodes by using different colors so as to highlight the node which needs the user's special attention, such as node 101, is very important. Such node could be one node or more nodes of the same type or different types. Such a requirement is also very common in other image or graphics field such as cartology.
In the related art, methods which only consider color contrast are commonly applied. There are many standards relating to color contrast. For instance, in a contrast ratio standard such as the Web Content Accessibility Guidelines 2.0 (http://www.w3org/TR/2008/CR-WCAG20-20080430/), stipulated by World Wide Web Consortium (referred to W3C for short, a nonprofit organization for stipulating web standard), the concept of contrast ratio is introduced and is defined as (L1+0.05)/(L2+0.05), the value of which is within a range of 1-21 (i.e. 1:1-21:1). It also defines contrast levels, and for example, the value of the contrast ratio which is capable of differentiating foreground and background strongly with colors is above 7:1 (AAA level). The minimum value of the contrast ratio which enables a user to differentiate the foreground and the background of a web page with colors is above 5:1 (AA level). For some colors, when the contrast level is determined, the highlighting color set (contrast color set) corresponding to the color is also determined according to a corresponding standard. Accordingly, those skilled in the art can also establish different contrast levels such as a four-star level and a five-star level in comparison to this standard according to different requirements, wherein:
L1 is relative luminance of the brighter color, L2 is relative luminance of the darker color;
The relative luminance (abbreviated as L thereinafter) is defined as:L=0.2126*R′+0.7152*G′+0.0722*B′
Where R′, G′, and B′ are calculated as follows:If RsRGB<=0.03928, then R′=RsRGB/12.92, otherwise R′=((RsRGB+0.055)/1.055)^2.4If GsRGB<=0.03928, then G′=GsRGB/12.92, otherwise G′=((GsRGB+0.055)/1.055)^2.4If BsRGB<=0.03928, then B′=BsRGB/12.92, otherwise B′=((BsRGB+0.055)/1.055)^2.4
RsRGB, GsRGB, and BsRGB are defined as:RsRGB=R8 bit/255GsRGB=G8 bit/255BsRGB=B8 bit/255
R8 bit, G8 bit, and B8 bit represent RGB values of colors, RGB color mode obtains various colors by varying the three color channels of red (R), green (G), and blue (B) and overlaying them to each other, wherein RGB are the colors representing the three channels of red, green, and blue.
As further exemplified, the hue difference standard (a fact standard) which is often used in the art introduces a concept of hue difference hue which is defined as:Δhue=|hue1−hue2|
wherein hue1 and hue2 are hue values (Hue) of two colors respectively, hue is a parameter of color mode HSV or HSB, that is, Hue, Saturation, Luminance Value or Brightness, Δhue is an angle between two colors on the hue ring as illustrated in FIG. 2, the value of the hue difference is within a range of 0-180°, and the HSV value of color and the aforementioned RGB value can be converted there between. When comparing two colors, the value of Δhue difference hue is larger, the contrast between the two colors is stronger, and thus the effect for the user to visually differentiate the two colors is better. Http://colorschemedesigner.com/previous/colorscheme2/index-en.html visually provides such a tool, by which when a user selects a background color, a foreground color in strong contrast with that background color can be displayed very conveniently. The hue differences of contrast levels—AAA, AA, A provided by the tool are respectively 180°, above 120°, and above 90°. Likewise, those skilled in the art can define different levels as required.
U.S. Pat. No. 6,463,173B, “System and method for histogram-based image contrast enhancement,” discloses a method of operating a computer to produce contrast enhanced digital images. The method commences with the step of producing a histogram having a first axis corresponding to a measurable property such as luminance and a second axis corresponding to a count of pixels having a particular value for the measurable property. This histogram is divided into clusters. Histogram equalization or stretching is performed on each cluster producing a modified histogram. The modified histogram is used to adjust the value of the first measurable property in the digital form, thereby producing a contrast enhanced image. The histogram is divided into clusters using a pattern matching technique. For example, patterns in the histogram that resemble Gaussian distributions and patterns that resemble uniform distributions are separated into individual clusters.
However, the above references just considered contrast colors per se, and cannot highlight information which needs user's special attention in an increasingly complicated chart. Currently, most of the related art performs comparison of a single color by manual interaction of the user, which is energy and time consuming and cannot obtain a good effect, as it usually requires the user to have professional knowledge about colors. Moreover, there are methods for assigning colors randomly, which usually neglect the information which needs a user's special attention.